Trends in the administration of COVID-19 vaccines with other vaccines in the United States reported to V-safe during December 14, 2020—May 19, 2023

ABSTRACT Introduction COVID-19 vaccines may be administered with other vaccines during the same healthcare visit. COVID-19 monovalent (Fall 2021) and bivalent (Fall 2022) vaccine recommendations coincided with annual seasonal influenza vaccination. Data describing the frequency of the co-administration of COVID-19 vaccines with other vaccines are limited. Methods We used V-safe, a voluntary smartphone-based U.S. safety surveillance system established by the CDC, to describe trends in the administration of COVID-19 vaccines with other vaccines reported to V-safe during December 14, 2020 – May 19, 2023. Results Of the 21 million COVID-19 vaccinations reported to V-safe, 2.2% (459,817) were administered with at least 1 other vaccine. Co-administration most frequently occurred during the first week of October 2023 (27,092; 44.1%). Most reports of co-administration included influenza vaccine (393,003; 85.5%). Co-administration was most frequently reported for registrants aged 6 months-6 years (4,872; 4.4%). Conclusion Reports of co-administration to V-safe peaked during October 2023, when influenza vaccination most often occurs, possibly reflecting increased opportunities for multiple vaccinations and greater acceptability of the co-administration of COVID-19 vaccine with other vaccines, especially influenza vaccine.


Introduction
Shortly after Emergency Use Authorizations (EUAs) were issued for the first COVID-19 vaccines in December 2020, the Centers for Disease Control and Prevention's (CDC) Advisory Committee on Immunization Practices (ACIP) recommended that COVID-19 vaccines be administered alone (i.e., without other vaccines).A minimum interval of 14 days was recommended between the administration of other vaccines, given the lack of data concerning the coadministration of COVID-19 vaccines with other vaccines. 1n May 2021, ACIP updated these recommendations based on accumulated experience, stating that the COVID-19 vaccines may be administered without regard for non-COVID-19 vaccination timing. 2 On September 23, 2021, ACIP recommended Pfizer-BioNTech COVID-19 monovalent booster doses for persons aged 18 years and older; booster doses of Moderna and Janssen vaccines were recommended on October 21, 2021. 3On September 1, 2022, COVID-19 bivalent booster doses were recommended for persons aged 12 years and older, and on October 12, 2022, Pfizer-BioNTech bivalent doses were recommended for children aged 5-11 years. 4These recommendations suggested that the peak in COVID-19 vaccination would coincide with the peak in annual seasonal influenza vaccination, which generally occurs during September and October.
Data describing the frequency of co-administration of COVID-19 vaccines with other vaccines are limited.We utilized V-safe data to estimate how the frequency of coadministration reflects updates to vaccine recommendations during December 2020-May 2023.

V-safe
V-safe is a voluntary smartphone-based vaccine safety surveillance system established by CDC in December 2020 to collect data on reactions and health impacts for registrants reporting COVID-19 vaccination. 5Following vaccination, persons registered themselves or their dependents with V-safe and selfreported information related to vaccination.Information collected included the registrant's age, sex, race, ethnicity, date of vaccination, COVID-19 vaccine manufacturer, dose number in vaccine series, and any vaccination(s) administered during the same healthcare visit.
V-safe COVID-19 vaccination data collection began on December 14, 2020, and concluded on May 19, 2023.From December 2020 through June 18, 2021, co-administration reports were retrospectively obtained by V-safe.On June 19, 2021, CDC added an item to the V-safe survey to capture if another vaccine had been received on the same day as a COVID-19 vaccine.Registrants answered "yes" or "no" to the item.A one-time survey was administered from October 28, 2021, through November 28, 2021, to retrospectively collect vaccine type(s) received among registrants reporting co-administration from June through November 21, 2021.On November 22, 2021, V-safe began prospectively collecting the type of vaccine administered during the same visit.Options for vaccine type received were agedependent; more than one vaccine could be selected.

Data analysis
Using the total number of COVID-19 vaccinations reported to V-safe as the denominator, we described vaccine coadministration by demographic characteristics, vaccine type(s) received, and trends over time during three influenza seasons (2020-21, 2021-22, and 2022-23). 6The reporting period for each influenza season began on Morbidity and Mortality Weekly Report (MMWR) week 40 and ended week 39 of the following year. 7We used SAS software, version 9.4 (SAS Institute Inc), to conduct analyses.
Reports were excluded if the COVID-19 vaccine manufacturer was listed as unknown (n = 13,051) or reported age at the time of vaccination did not meet EUA requirements for the reported vaccine received (n = 6,052) to limit inaccurate vaccination reports.

Human subjects
This activity was reviewed by the CDC and was conducted consistent with applicable federal law and CDC policy.

Discussion
In V-safe, reports of vaccines administered with COVID-19 vaccine were uncommon during the 2020-21 influenza season; co-administration was not recommended until May 2021, after the influenza season.COVID-19 booster vaccine recommendations coincided with the peak timing for annual influenza vaccination, increasing the likelihood for co-administration of COVID-19 vaccines with influenza vaccines.Receipt of multiple vaccines during the 2021-22 and 2022-23 seasons was most common during September and October, when most annual influenza vaccines are administered. 8A study describing the administration of bivalent COVID-19 vaccines with influenza vaccines using data from the Vaccine Safety Datalink (VSD) found similar vaccination patterns. 9nfluenza vaccines were the most common vaccines administered with COVID-19 vaccines in V-safe data.Annual seasonal influenza vaccination is recommended for all persons aged 6 months and older who do not have a contraindication. 10he co-administration of influenza vaccines with other vaccines including measles, mumps, and rubella (MMR), varicella, pneumococcal, and tetanus-containing vaccines is safe, based on extensive clinical experience and observational data. 11][14][15] Over 97% of co-administrations reported to V-safe were from adults aged ≥18 years, reflecting overall trends in COVID-19 vaccine coverage.As of June 2023, 88.0% of adults were estimated to have received at least one COVID-19 dose, compared to 36.8% of children. 16However, the receipt of two or more vaccines in addition to a COVID-19 vaccine was most common among children aged 6 months-6 years (28%).This finding reflects the recommended routine childhood immunization schedule, which often includes more than one vaccination at healthcare visits from 2 months to 6 years of age. 17istorically, the adult immunization schedule has provided fewer opportunities for co-administration. 18Survey results reported by the CDC found relatively high levels (72%) of acceptability of co-administration of influenza vaccines with COVID-19 vaccine among adults. 19On June 21, 2023, ACIP recommended that adults aged ≥60 years may receive a single dose of a respiratory syncytial virus (RSV) vaccine. 20The addition of COVID-19 and RSV vaccines to the adult immunization schedule suggests education about recommendations for the administration of multiple vaccines during a single healthcare visit could lead to improved vaccine coverage in adult populations. 18

Limitations
V-safe is a voluntary program; data might not be representative of the vaccinated population.Recall bias and lack of verification concerning vaccinations received may have resulted in misclassification of vaccination data.Reasons for the increased uptake in co-administration cannot be determined as specific questions were not included in V-safe surveys.

Conclusions
Reports of administration of COVID-19 and other vaccines to V-safe were highest during the 2022-23 influenza season, possibly reflecting greater acceptability of co-administration of COVID-19 vaccine with other vaccines, especially influenza vaccines.

Figure 1 .
Figure 1.Reports of COVID-19 vaccines co-administered with another vaccine received by V-safe.a Proportion of reports indicating a COVID-19 vaccine coadministration with another vaccine during the same healthcare visit b The reporting period for each influenza season begins in MMWR week 40 and ends week 39 of the following year.For the reporting period of the 2020-21 influenza season, data collection began on December 14, 2020, during MMWR week 51, and ended on October 2, 2021.The reporting period for the 2021-22 influenza season began on October 3, 2021, and ended on October 1, 2022.The reporting period for the 2022-23 influenza season began on October 2, 2022; the study period is through MMWR week 20.
19, 2021, Division of Healthcare Quality Promotion, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd., NE, Atlanta, GA 30333, USA.

Table 1 .
Frequencies of COVID-19 vaccine co-administration among reports (N = 21,048,557) received by V-safe by influenza season a .
No: Number of reports indicating a co-administration received by V-safe.N: Total number of COVID-19 vaccinations reported to V-safe.AI/AN: American Indian/Alaska Native; NHPI: Native Hawaiian/Pacific Islander.a The reporting period for each Influenza season begins MMWR week 40 and ends week 39 of the following year.b Data collection for the 2020-21 influenza season began on December 14, 2020, during MMWR week 51, and ended on October 2, 2021.c The reporting period for 2021-22 influenza season began on October 3, 2021, and ended on October 1, 2022.d The reporting period for the 2022-23 influenza season began on October 2, 2022; the study period is through MMWR week 20.e Other or prefer not to say.− Not applicable.

Table 2 .
Type of vaccine(s) administered with a COVID-19 vaccine among reports (N = 21,048,557) received by V-safe.Category is not exclusive; more than one vaccine type could be selected by registrant.− No reports for this type. a

Table 3 .
Number of vaccines received in addition to a COVID-19 vaccine received by V-safe.